Insulation Scope of Work: Template and Checklist for Commercial GCs

Insulation is one of the most technically varied trades in commercial construction — and one of the most frequently under-scoped. A single building envelope can require cavity insulation, rigid continuous insulation, spray polyurethane foam (SPF), pipe insulation, duct wrap, equipment insulation, and fire-rated thermal barriers — each with different R-value requirements, vapor control strategies, and installation standards. A vague insulation scope of work creates gaps between trades, energy code compliance failures, and expensive re-work. This guide covers the sub-trade requirements, package deliverables, and coordination checkpoints that every PM and estimator needs.

Define insulation scope by location and system — not as a single line item. Walls, roofs, below-grade assemblies, mechanical systems, and fire-rated conditions each have distinct requirements.

Batt and Blanket Insulation

• Fiberglass batt: Most common for wood-framed wall cavities and attic floors. Specify R-value (not thickness alone), width to match stud spacing (15" for 16" o.c., 23" for 24" o.c.), and faced vs. unfaced. For walls: kraft-faced batts with facing toward the warm-in-winter side (interior). For attics: unfaced batts at the floor level or blown-in loose fill.
• Mineral wool (rock wool) batt: Higher fire and acoustic performance than fiberglass. Specify where fire-rated wall assemblies or STC-rated partitions require non-combustible insulation. Mineral wool is non-combustible and retains performance at temperatures up to 1,200°C — required in some UL fire-rated steel stud assemblies.
• Continuous batt in metal stud walls: Metal studs conduct heat. For exterior walls with metal framing, require continuous insulation (CI) on the exterior face of the stud to break the thermal bridge. This is an energy code requirement in most jurisdictions under ASHRAE 90.1.

Rigid Board Insulation

• Extruded polystyrene (XPS): For below-grade foundation walls, under-slab, and inverted (protected membrane) roof assemblies. R-5 per inch. Specify board thickness per the energy model, and whether the insulation is to be protected from UV and physical damage.
• Polyisocyanurate (Polyiso): Highest R-value per inch (R-6 to R-6.5) for roofing assemblies. Specify faced or unfaced, required R-value, and any tapered system for roof drainage. Polyiso loses effective R-value in cold temperatures — account for this in climate zone calculations.
• Expanded polystyrene (EPS): For below-grade applications and under-slab where moisture resistance is critical but cost needs to be controlled. Lower R-value than XPS but more vapor-open — confirm compatibility with the vapor control strategy.

Spray Polyurethane Foam (SPF)

• Open-cell (0.5 lb/cf): For interior cavity fills, sound attenuation. Not suitable for exterior use without a vapor barrier. R-3.7 per inch. Specify where open-cell is acceptable vs. where closed-cell is required.
• Closed-cell (2.0 lb/cf): For exterior walls, rim joists, unvented roofing assemblies, and anywhere a vapor retarder is required. R-6 to R-7 per inch. Defines the air and vapor barrier in one application. Specify minimum thickness per energy code compliance requirements.
• Thermal barrier requirement: Exposed SPF foam must be covered by a thermal barrier (minimum ½" gypsum board per IBC Section 2603.4) unless the foam has passed NFPA 286 room corner testing. This is missed on almost every exposed-SPF project — define thermal barrier responsibility in the insulation or drywall scope explicitly.

Mechanical System Insulation

• Pipe insulation: Specify insulation type (fiberglass, elastomeric foam, calcium silicate for high-temp), thickness per ASHRAE 90.1 Table 6.8.3 (based on fluid temperature and pipe diameter), jacket type (ASJ all-service jacket, PVC, canvas), and vapor barrier requirements for cold-water piping.
• Duct wrap and duct liner: HVAC ductwork in unconditioned spaces requires external duct wrap (minimum R-6 per energy code, R-8 in attic spaces). Internal duct liner is used for acoustic control in occupied spaces — specify where each is required and confirm with the HVAC sub that liner is accounted for in duct sizing.
• Equipment insulation: Tanks, vessels, heat exchangers, and roof-top equipment. Specify insulation system type (flexible cellular, mineral wool board) and jacketing.

Tip for PMs: The most common insulation scope gap is the thermal barrier over exposed SPF foam. Building inspectors regularly flag this at framing inspection. If your framing or insulation scope does not include this, expect a change order from one of those trades — or a failed inspection.

Insulation submittals must demonstrate energy code compliance — not just material delivery. The building envelope thermal performance must be documented at permit.

Required Submittals

• Product data sheets for all insulation products — including R-value per inch, vapor permeance (perms), fire classification (ASTM E84 flame spread and smoke developed index), and applicable standards (ASTM C665, C591, C578, C612, etc.)
• Energy code compliance documentation: COMcheck (U.S.) or equivalent showing assembly U-values meet or exceed the energy code for the project's climate zone
• SPF foam contractor qualifications: installer certification (SPFA Professional Certification, ICAA, or equivalent) and product-specific training records
• UL listing numbers for insulation used in UL-listed fire-resistant assemblies
• MSDS/SDS for all spray-applied products

Vapor Control Strategy

• Define the vapor control approach for each wall and roof assembly: vapor retarder class I (≤0.1 perm), Class II (≤1.0 perm), or Class III (≤10 perms) per ASHRAE 189.1 or IBC. In mixed climate zones, a smart vapor retarder (Class III or Class II/III variable) may be required to allow drying in both directions.
• Vapor barrier continuity must be addressed at all penetrations, connections, and transitions. Define lap, seal, and tie-back requirements in the scope.

Best Practices from Leading GCs

• Coordinate insulation scope with the air barrier sub if air and vapor control are separate scopes. Many energy code failures result from misaligned responsibilities at the wall-to-roof intersection and at window/door rough openings.
• For SPF work, require the sub to post air quality and re-entry notices per OSHA and EPA guidance. SPF application creates off-gassing that requires building evacuation during and after application.
• For pipe insulation, verify that the HVAC sub's scope includes or excludes insulation on flexible duct connections, terminal units, and VAV boxes. These items are frequently in a grey zone between the mechanical and insulation scopes.

Insulation is installed in multiple phases throughout construction — envelope insulation during framing, mechanical insulation during mechanical rough-in, and roofing insulation during the roofing package. Each phase has its own coordination dependencies.

Envelope Insulation Sequencing

• Wall cavity insulation installs after framing inspection, MEP rough-in inspection, and window installation (for continuous insulation on the exterior). Do not allow drywall boarding until insulation is inspected and confirmed complete.
• For below-grade insulation, install rigid board insulation to foundation walls before waterproofing membrane is covered by drainage board and backfill. Sequence with the waterproofing sub.
• Roofing insulation installs per the roofing sub's sequence — confirm whether insulation is supplied by the roofing sub or the insulation sub. Grey area that must be resolved before RFP.

Mechanical Insulation Sequencing

• Pipe insulation follows mechanical rough-in and pressure testing — insulation cannot be installed over untested piping. Confirm that the mechanical sub will complete pressure tests before insulation begins.
• Define whether pipe insulation is in the mechanical sub's scope or the insulation sub's scope. Industry practice varies: some GCs keep all insulation with the insulation sub; others allow mechanical subs to include pipe insulation in their scope. Pick one approach and be explicit.

Pre-Installation Coordination Checklist

• Framing inspection passed before wall cavity insulation
• MEP rough-in inspection passed in all cavities
• Window and door installation complete before continuous exterior insulation
• Plumbing and HVAC pressure tests complete before pipe/duct insulation
• Thermal barrier responsibility defined for all exposed SPF applications
• Energy code compliance documentation reviewed and accepted by building official
• Vapor control continuity at all penetrations and transitions confirmed

Tip for Estimators: When reviewing an insulation bid, check whether it includes all mechanical insulation or only envelope insulation. Pipe insulation for a medium-sized commercial building can represent 30–40% of the total insulation contract value and is frequently excluded from a "building insulation" bid without being explicitly stated.